The invention relates to a take-over and positioning device and to a method for being able to place a film, which is used as a core for a sheathed-core tablet, in the die of a tablet press.
The prior art describes rotary tablet presses, for example for the pharmaceutical industry, by means of which standard single-layer tablets, multi-layer tablets and/or sheathed-core tablets can be produced. In particular, the production of sheathed-core tablets is highly complicated since a tablet has located in it a second tablet, which is known as a core.
The tablet presses suitable for the production of sheathed tablets have in the sheathed-core version, on the reference circle of the die plate of a tablet press, not only one, but, in particular, two filling appliances for powder. These two powder filling appliances contain the powder with which the core of a sheathed-core tablet is sheathed.
In order to achieve such sheathing, between the two powder filling appliances of the tablet press a core module is located, via which the prefabricated cores to be sheathed are introduced individually into the die of a rotary tablet press. The cores to be sheathed are conventionally fed to the core module as bulk material.
The actual pressing operation for the production of sheathed tablets takes place in that, first, powder is poured into the die of the tablet press via the first powder filling appliance, and then the core to be sheathed is introduced into the die by means of the core module. The inserted core is covered with powder by means of the second powder filling appliance, the powder is finally compacted as a result of the last pressing operation, and a solid envelope, what is known as the sheath, is thereby generated around the core.
During the production of the sheathed-core tablet, the pressure force upon each individual sheathed-core tablet is monitored. Should no core or only parts of a core have been inserted, the pressure force falls below the lower check limit, and the tablet is recognized as defective and is sorted out automatically via a pneumatic switch. It can thereby be ensured that every sheathed-core tablet also actually has a core.
EP 2 110 232 A2 describes a method and an apparatus for the insertion of cores in dies of a rotary tablet press. In this case, a feed chain for the cores of sheathed-core tablets is described, which is composed of a core separator, of a core feed device and of a core distributor. In this case, the cores to be inserted into the dies are fed to the core feed device via the core separator and are introduced into orifices on a rotatable conveyor. The cores are transported to the core distributor by means of this conveyor, the guide surface, on which the rotatable conveyor lies, being interrupted in the region of the core distributor, so that the cores located in the orifices fall downward and are picked up by gripping elements of the core distributor which are designed as grip tongues. The grip tongues transport the cores into the region of the rotor of the rotary tablet press, where they are deposited into a die at the overlap point of the reference circle of the die plate of the rotary press and of the reference circle of the rotatable conveyor. The disadvantage of the apparatus described in EP 2 110 232 A2 is that, according to this invention, no sensor check of the cores is carried out before they are deposited into the die.
Further, the apparatus described in EP 2 110 232 A2 and the method described there are not suitable for processing films as inserts of a sheathed-core tablet to be produced. Films in the context of this invention are preferably information carriers, separating layers or active substance carriers which are lightweight, flexurally slack, pliant, flexible, rigid and/or electrostatically chargeable. They have a diameter of approximately 3 to 20 mm and a preferred thickness of 0.1 to 0.5 mm. It may be gathered from these features that the apparatus described in EP 2 110 232 A2, by virtue of its design, is unsuitable for transporting these films or for depositing them reproducibly into the dies of the rotary tablet press at the required speed.
EP 2 110 232 A2 is aimed, further, at the feed of the cores from an indeterminate quantity, which may be implemented, for example, by means of bulk material feed. Such a method is out of the question for films in that, because of the electrostatic charge, they would as a bulk material, for example, stick together or, on account of their flexural slackness, would not be grasped by the grip tongues of the core distributor. Furthermore, films, as core inserters, require individual guided transport which does not give the individual film any degree of freedom for leaving the production region of the rotary tablet press by means of air vortices or other disturbances. The core feed device with the orifices through which the cores fall to the core distributor in the transfer region does not fulfill this requirement.
EP 0 349 777 A1 describes a sheathed-core press for the production of sheathed tablets, in which core rams, as they are known, are provided, by means of which tablet cores are deposited into a die into the first powder layer of a tablet to be pressed. For transferring the cores, EP 0 349 777 A1 makes use of movable arms. This is intended to achieve the object of introducing the cores into the powder layer in an exactly centered manner, particularly when the die table rotates at a high rotational speed. The disadvantage of the sheathed-core press described in EP 0 349 777 A1 is that the core feed and the transfer of the cores to the movable arms are not suitable for the use of flexible, flexurally slack films.